Electrical grimlins --Electrician being straight?

[linus]

We recently bought a new house (about 3 years old). The house inpsector pointed out that the outlet located above the laundry sink needed to be a GFCI and wasn't. The seller paid to have a licensed electrician come out and put one in. The problem is that now when we turn the washer on, the GFCI trips. We called the electrician back he said it was a typical nusiance trip, but agreed to try a new GFCI with no improvement. The GFCI receptacle is the first of a 4 outlet 20A dedicated circut for the laundry room, that comes off of a 200A main. One of the down stream GFCI protected outlets is for the washer. His solution is to pay him $$$ to run a dedicated 20a circut just for the washer. The washer is brand new and the electrician did not think there is anything wrong with it and says that nusiance trips with big appliances are a common problem. I've reinstalled the original outlet for now just so we could use the washer, but know we need to have the GFCI above the sink for safety. Anyone have any other suggestions? Can't I simply have the GFI serve only the one outlet rather than the entire circut? The outlet for the washer is about 3' from the sink.

Second issue is that when we use the garbage disposal or other high draw kitchen appliance the lights in half of the house dim momentarily. The affected area is served by a 100A sub panel supplied by the 200A main. The same electrician said the problem is that the wire supplying the sub panel is the minimum size allowed by code, but still not big enough in his opinion. His solutions is to pull a new larger guage wire to the sub panel for yet more $$$. My question is that how can it be large enough by code, but still not large enough to prevent the momentary dimming of lights. Is this indicative of a bigger problem?

[Duhandyman]

Here's the deal. Yes you need a GFI above the sink. Depending on where these other recepts are on the circuit you may need to have them GFI protected as well. What can be done is to "pigtail" the wires at the sink for the GFI and then install a Single (1 actual plug) at washer and then install a GFI at the next recept on the line with the load side protecting the remaining recepts. Nuisance tripping in this intance is the result putting an appliance on a GFI where the start up of the motor is faking the GFI out and making it think it has a ground fault.

The issue with the lights and the appliance you may in fact have those lights on the same circuit as that garbage disposal. His opinion about the size of the wire is just that. If the code says that the current wire size is apropriate for the conditions then more then likely the wire size is accurate and the problem lies in needing another actual dedicated circuit for each of those "big" appliances. New code states that you need independent circuits for most kitchen appliances.

I hope this helps. Let us know if you need more advice.

[pcboss]

Even if a new circuit were run for the washer it would still require GFI protection within 6' of the laundry tub.

I am not sure why a new washer is nuisance tripping a new GFI. New GFIs are less prone to motor loads than the older ones.

[ibpooks]

the electrician did not think there is anything wrong with it and says that nusiance trips with big appliances are a common problem.

I wouldn't call them common anymore, but they certainly do happen.

Anyone have any other suggestions?

Perhaps you already did this, but try a different brand of GFCI receptacle such as a Cooper or a Pass-Seymour; avoid the cheap store brands. Also try plugging the washer directly into the GFCI with the downstream receptacles disconnected in order to confirm that this is a problem only with the washer and GFCI. I would try a GFCI breaker next; it's about $40, but still cheaper than re-pulling the circuit. I don't think that re-pulling the circuit will accomplish anything in my opinion; if the wire was bad the GFCI would trip without any loads plugged in. In your case it seems that only the washer is a problem; did you try plugging other things in at the washer receptacle to see if there's a trip?

Can't I simply have the GFI serve only the one outlet rather than the entire circut? The outlet for the washer is about 3' from the sink.

All receptacles must be protected within 6' of the sink. All must be protected if the laundry is in an unfinished basement room.

said the problem is that the wire supplying the sub panel is the minimum size allowed by code, but still not big enough in his opinion.

His explanation is plausible, but there could be more factors in play too. Without knowing more details for myself I can't say for sure that's the problem, but it is reasonable.

how can it be large enough by code, but still not large enough to prevent the momentary dimming of lights. Is this indicative of a bigger problem?

The code is a minimum safety standard, not a design guide. That is to say it only tells us how to make electrical systems safe and functional but not necessarily pretty.

[thinman]

Is the washer supplied from a 15 or 20 amp circuit breaker?

How far is the sub panel from the main panel? What circuits are fed from the sub panel?

[PATTBAA]

It could be construed that the words " 100 amp sub-panel" simply describes the rating of the panel only ; the "dimming" problem calls into question the ampacity of the Feeder Conductors that supply the panel.

If the ampacity of the Feeder Conductors = 100 amps, it's very doubtful that the disposal motor-current would cause a voltage-drop that would result the dimming.The rating of the breaker that protects the Feeder to the S-P should indicate the size of the conductors.

It's possible that Feeder Conductors are not 100 amp conductors , or that the starting-surge of the disposal motor causes a very brief "blink" in the liting-circuits .

If you connect a "heavy" load on the panel, and there is a definite and constant voltage drop, a defective connection could be the problem.

[Tolyn Ironhand]

I doubt changing the feeders to the sub panel would make that big of a difference. When you hit the disposal, the motor draws around three times of the normal running current. It is nothing to worry about but if it bothers you, see if he can move the disposal breaker to the opposite phase of the lights.

[linus]

Thanks. In regards to the washer tripping the GFCI, will go find a high quality GFCI outlet as the one he installed looks pretty generic. It is a 20A circuit. If that doesn't work, I'll call Sears out and have them check out the washer. If it checks out ok, only then will I have a new dedicated line circuit brought in. FYI, I think the electrician can move the outlet to the far side of the washer and clear the 6' rom sink requirement.

To answer questions in various replies to the dimming of the lights: It isn't only the disposal. The blender, food processor, etc all yield the same result. Disposal is on a dedicated circuit, as is the dish washer. (3 separate circuits feed two duplex receptacles under the sink. Two other dedicated 20A circuits supply the kitchen outlets, and one dedicated to the fridge and one to the microwave.) In addition to the kitchen, the sub panel supplies juice to a master bed/bath, half bath, garage, and dining room. The sub panel is serviced by 2 125a breakers on the main....so I guess the sub is actually a 125a. Sub panel is approx 60 ft from the main (opposite side of the house.)

Pattba, where would I look for a faulty connection? Any easy way to check?

[thinman]

Thanks. In regards to the washer tripping the GFCI, will go find a high quality GFCI outlet as the one he installed looks pretty generic. It is a 20A circuit.

Install a 20 amp GFCI and see what happens if you haven't tried that already.

[pcboss]

Install a 20 amp GFCI and see what happens if you haven't tried that already.

The difference between a 15 and 20 amp GFI or receptacle is the shape of the slots. The internals are the same.

[ibpooks]

The sub panel is serviced by 2 125a breakers on the main....so I guess the sub is actually a 125a. Sub panel is approx 60 ft from the main (opposite side of the house.)

Now that is strange. Basic kitchen appliances should not be able to cause that much voltage drop in a 125A feeder at 60'.

Pattba, where would I look for a faulty connection? Any easy way to check?

It would be either where the feeder wires connect in the subpanel or where they connect in the main panel. Although I have seen this problem from a loose connection in the service entrance or at the power company transformer. Sometimes even a defective or undersized transformer can cause abnormal dimming.

One more question -- if you have a central air conditioner or heat pump, do you notice lights dimming when that unit kicks on? Can you determine if it only happens on circuits fed from the subpanel or also with circuits on the main panel?

[linus]

One more question -- if you have a central air conditioner or heat pump, do you notice lights dimming when that unit kicks on? Can you determine if it only happens on circuits fed from the subpanel or also with circuits on the main panel?[/QUOTE]


Thanks for your reply. No AC only a heater, and it is fed from the main panel. I've only noticed the lights blinking on the circuts associated with the sub panel.

[thinman]

The difference between a 15 and 20 amp GFI or receptacle is the shape of the slots. The internals are the same.

Well, speaking from experience i install 20 amp GFCI receptacles on constructions sites because 15 amp GFCIs trip because of power tools.

[pcboss]

In order to be provide GFI protection for people both the 15 and 20 amp GFIs should trip between 4-6 mA of unbalanced current.


I don't know why you are seeing a difference. If you said the breaker was tripping I could understand that.

[John Nelson]

Well, speaking from experience i install 20 amp GFCI receptacles on constructions sites because 15 amp GFCIs trip because of power tools.

That doesn't make any sense to me either.

[thinman]

Guess it's one of those unexplainable electrical things. Maybe the 15 amp GFCI trips because of the length of the extension cord from the GFCI receptacle to the user's end. Or a 20 amp GFCI receptacle can tolerate motor in-rush current better than a 15 amp GFCI.

Anyway back to the OP's problem. Can you bypass the non-GFCI receptacles so that only the GFCI and washer receptacles are energized? Then try using the washer and see if the GFCI still trips. If it does, then I would check to see if the electrical connections at all of the receptalces are correct.

[linus]

Well, I replaced the GFI with a new 20A and replaced the receptacle supplying the washer -- no luck. I did validate that the problem is not the washer as it doesn't trip in other outlets AND any other load besides the washer will trip the GFI at that outlet.

I decided to tear into this myself this weekend and this is what I found. I'll try and be as susinct as possible.

The receptacle for the washer that trips the GFI is only connected to the GFI on the neutal leg. The circut is fed by a 3 wire romex. The hot black and white neutral feed through the GFI and feed all of the outlets in the laundry room. The hot red goes directly to the washer outlet and the neutral comes off of the GFI. (Note the black from the 3 wire romex along with the common neutral from the 3 wire romex continue beyond the washer outlet to feed 2 additional outlets.

The 3 wire romex is supplied by 2 20A breakers.

Can this be the problem? Can the fact that only the neutral sits behind the GFI cause it to trip? Can I simply install a second GFI behind the the first one where only the neutal is connected without it continuing to trip? The outlet box is within 6' of the sink so it needs to be protected.

[John Nelson]

Okay, I didn't read through this whole post to see if this question had already been answered. If you plug a lamp into this receptacle instead of the washing machine, does it also trip the GFCI?

And yes, it does sound like your GFCI is incorrectly wired. In fact, it sounds like it was wired by someone with absolutely no understanding of how a GFCI works. GFCI and shared-neutral circuits are inherently incompatible (I say this often). There are ways around it, however. The simplest is to use a separate GFCI receptacle in every outlet, using only the LINE side conections and never using the LOAD side connections.

[ray2047]

The seller paid to have a licensed electrician come out and put one in. The problem is that now when we turn the washer on, the GFCI trips. We called the electrician back he said it was a typical nuisance trip, but agreed to try a new GFCI with no improvement.

You might want to call the seller and have him get the electrician back. Assuming this is on a two pole breaker the electrician should have been aware of the possibility of it being on a multi-wire circuit. If I read correctly he installed two not one GFCI. Did he install them without turning off the breaker? That could be why he didn't catch it but he should be willing to correct his mistake.

[ibpooks]

...hot black and white neutral...hot red goes directly to the washer outlet and the neutral comes off of the GFI...(Note the black from the 3 wire romex along with the common neutral from the 3 wire romex continue beyond the washer outlet to feed 2 additional outlets.

Can this be the problem?

This is for sure the problem. A GFCI cannot work on a shared neutral circuit. You can correct the problem either by having the electrician back out to fix his very amateur mistake or by doing this yourself.

You'll need to install a GFCI at each receptacle location wired only to the LINE side; no wires on the LOAD side. Each GFCI receptacle will have only a ground wire, a hot wire on the brass LINE terminal, and the neutral on the silver LINE terminal.

[ray2047]

Just to add a bit if there are two sets of wires in the box they must be connected together and pigtailed. The pigtail goes to the line side as already stated.

On more expensive GFCIs with side compression fasteners there may be notches for two wires on each of the line connectors. In that case only the ground needs to be pigtailed.

[linus]

Thanks to all. This makes sense and I'll give it a go this weekend or next. I'm glad I decided to dig into this myself....even learned a bit along the way. I'm not sure why the electrician didn't catch this, but at least provides a plausable explaination why he wanted to bring in a new dedicated circut